Coaxial combustion products generator, turbine, and compressors



Dec. 8, 1953 J. A, PETRIE 2,661,594

COAXIAL COMBUSTION PRODUCTS GENERATOR,

TURBINE, AND COMPRESSORS Original Filed Oct. 20, 1949 2 SheetsSheet l JAMES A. PETNE.

Patented 8, 1953 U ITED :EPAQENT 'G ZF EI CLE @COAXIAL COIVIBUSTIONZPRODHCTS" GENER- ATOR,"J TURBINE, AND EOMPRE SSORS I James AlexamiderPetrie, Lit'tleover, England, as-

when: company "z'Claims. "I This application is divided out of mycopending application Serial No. 122,440 filed October-20,

949, nowPatent No. 2,625,790.

turbines, compressors, fans and fluid screws. Thus some axialfiow turbines, whenproducing torque bythe passage of fluid through their rotor blading, also have an axial thrust generated on the rotor disc or drum whichis approximately proportional to the torque. :Likewise, in the "case of an axial fiow compressor, ifanlor-fluid screw, the absorption of power thereby may be accompanied by an axial thrust on the rotor which again may be approximately proportional to-thedriving torque. In the case of single-:sidedradiaL-flow machines a similar thrust mayarisedue to unbalance of pressureiloadingsvonthe two sides of the rotor. For example, inthe case'of :a radial flow turbine or asingle-sided centrifugal compressor the fluid pressure loading will .differr-as between the side of the rotorcarryingemoving blading or vanes and that which is subjected either to static inlet exhaust or ambient; pressure.

The object of the invention. is to. provide-novel constructions of gas-turbine engines in which .the various rotors can be independently rlocated axially.

The invention maybe more readilyrappreciated from the following description .ofv-agas-turbine engine which embodies the invention, reference (being hadtothe accompanying drawingin which:

Figure 1 illustrates the gas-turbine engine part1y in section, and

Figure 2'is an exploded View of the shaft and gear connections with parts broken, with partsnin section and with parts iii-elevation.

In the drawing, a turbine I59 drives two-centrifugal compressors 151,. I52 which are coaxially arranged with the turbine LEE! and tin -addition the turbine i553 drives an v.airscrew through .a "reduction gear generally indicatedby-the reference numeral I 53. (Air enters the firstcompressor Pi! in which .it 'is compressed and Ifrom which lit 1 is delivered to'the entry of the second compressor I52. 'vFrom the delivery ofsthe-secon d compressor 1 5 2 itpasses after heating to the-turbine1l-50 iIt isfdesirable thati'theltwo compressors 5 l 1-52, .aiidl'the turbine? I56 should be located "independ- =ently .of one another. LTo .this end the turbine i shaft l 5'5 which ".isilocatdiby. 4a lthrust bearing "(54' has a sleeve: i 56 engageditherewith by. normal vsplines i5? V and T thessleeve Thas internaf helical splines il 58 at Ithe -end remotemfrom' the l turbine sham the sleeve (56'. isifheld; in engagement with .the turbine "shaftlby aimit'l'59. T'Ihei high picsi sure compressor shaft": [5 0'.h-as formed, at theiend thereof it adjacent. to "the turbine; external vhelical splines 16! whichme'sh w'ith'the' internal-isplines F58 forme'don'the'sleeve'if56, the sense andiangle df'the"hlix are chosen sol'ih'ttthe 'leeld.f the helical splines I58 is in thesames'ense as the di'rection-of'rtation, ire. sothat the shaftlfifi 'andsl'e'eve l 56tendtd'bedrawn' together in opera- 20 'ition and'the thrust 'jgenerated as a' result of the transmission oftorquethroughfthhelical splines a. [58, "I 5! and transmitted "to "the ftlli'bine 'Shtft through'fthe nut! 59 "at'l'ea'stfpartially fca'ncls out lthe "out-of-balanc'e "thr'u's't "6f the turbine, and

Zthethrust"treinsrriittdto'the highpres'surecoinpressor shaft 1'60 "opposes .tlieftl'irust diieto the rotor of thecompressor ['52. lThe l'iighl-pre'ssure compressor shaft is *rocate'niby a "thrust bearing {'52. "The term 6f "the Thigh jpre'ssure compressor shaft fseremote fromtne'turbine isformeuwith extermifhiicl splines? r .dfwhichftl'leleafd is inthesa'mesense astlre-di'rectionbf rotationfanu which engage with co-operating internalhelical splines I at the rear end of the. lowpr'essure compressor'shaft gfsi. Thusftne twocompressor "shafts" I Stand if 61 terfd to be 'drawn 'togetherin operation: and "a rearward "thrust is produced in itrrelowpressure compressorshaft"1'61 "as arsiilt Iof thetraiisn'iissionof "torjqueith'r ough the 'h'e'li'cal 'i'splinesfl 65 166 wliih "opposes the thrust "dueito tire-rotor Gfthe compressorilsl. The' low pressure compressor shaft 'is l'oc'atedby a thrust -bearing F63.

The for'w'arcl end dfltheflow pressurecompressor -shaft i I 5:! is formed with another set of. internal helical splines'l'fiii-of whichthellead isin the-same sense aslthetdirection.di-rotationand-whichmesh withaico-operating setfiof external splines (I 69 'on ansinterme'diate .idriveishaftil'm, so that the shaft ""31 andthe shaft tend to be drawn together in operation. This intermediate drive shaft ili'i is located by a thrust bearing ill carried by a diaphragm I 12. The same diaphragm I72 supports the rear bearing [13 which locates a layshaft N4 of the reduction gear I53. A roller bearing 116 supported by a second diaphragm I'll carries the front end of the layshaft I'M.

Two reduction gear pinions are, He are mounted on the layshaft lid to rotate therewith and the drive is transmitted from the intermediate shaft Hi! to the rear layshaft pinion H8 which has helical teeth, of which the lead is in the opposite sense to the direction of rotation of the layshaft l'i l so as to produce a forward thrust in the intermediate shaft Hi3 and a rearward thrust in the layshaft pinion lit which tends to draw the pinion lit and the shaft liQ together. The second layshaft pinion I79 meshes with an internal annular gear ifii carried by the airscrew shaft M2, the latter being located by a thrust bearing 583 supported in the reduction gear housing. The second layshaft pinion We and the annular gear Isl also have helical teeth, the lead of the teeth on the pinion Iii! being in the same sense as the direction of rotation of the layshaft Hi4 so as to produce a forward thrust in the layshaft I'i l, thus tending to draw the layshaft I18 and the gear l8! together and to balance the rearward thrust in the layshaft due to the first pinion lit and enabling the locating bearing H3 to be of reduced capacity. The rearward thrust produced in the annular gear i3! opposes the thrust in the irscrew shaft I82 due to the airscrew and thus permits an airscrew shaft thrust locating bearing I83 of reduced capacity to be used.

It will be seen that by appropriate selection of the helix angle, the reactions produced by the helices in their respective shafts may be arranged so that the loads in such shafts are substantially balanced, so that small capacity thrust bearings may be used.

It will be appreciated that in the interconnection of turbine and compressor or fluid screw systems in accordance with the invention, the thrust arising n the systems in operation is approximately proportional to the torque transmitted thereto or therefrom, and consequently throughout the designed range of running, the degree of balance afforded by the adoption of the invention will be maintained irrespective of the power transmitted.

The invention further permits the independent axial location of the various items of the assembly, which is of importance, in order to maintain efficiency of operation of these items, particularly in the case of axial flow compressors and turbines.

I claim:

1. A gas-turbine engine comprising a first compressor casing having an inlet and outlet; a first compressor rotor in said first compressor casing and on which when in operation, a first axial load is generated; a first compressor shaft on which said first compressor rotor is mounted for rotation therewith and to which said first axial load is transmitted; a second compressor casing having an inlet and an outlet; ducting from the outlet of said first compressor casing to the inlet of said second compressor casing, a second compressor rotor in said second compressor casing coaxial with said first compressor rotor and on which, when in operation, a second axial load in the same direction as said first axial load is generated; a second compressor ing to the inlet of said turbine casing and including heating means; a turbine rotor in said turbine casing, coaxial with said first and second compressor rotors and on which when in operation a third axial load in the opposite direction to said first and second axial loads is generated; a turbine shaft on which said turbine rotor is mounted for rotation therewith and to which said third axial load is transmitted; a first pair of sets of interengaging helical splines, the one on-said second compressor shaft and the other on said turbine shaft, whereby torque can be transmitted from said turbine shaft to said second compressor shaft and whereof the helix lead on said turbine shaft is in the same sense as the direction of rotation so that when torque is so transmitted a fourth axial load is generated in said turbine shaft opposing said third axial load and so that a fifth axial load is generated in said second compressor shaft opposing said second axial load; a second pair of sets of interengaging helical splines, the one on said first compressor shaft and the other on said second compressor shaft, whereby torque can be transmitted from said second compressor shaft to said first compressor shaft and whereof the helix lead on said second Compressor shaft is in the same sense as the direction of rotation so that when torque isso transmitted a sixth axial load is generated in said first compressor shaft opposing said first axial load; a first locating thrust bearing for said first compressor shaft; a second locating thrust bearing for said second compressor shaft; and a third locating thrust bearing for said turbine shaft.

2. A gas-turbine engine as claimed in claim 1 and further comprising a fiuidscrew on which,

when in operation, a seventh axial load is generated in the same direction as said first axial load; a fluidscrew shaft on which said fiuidsorew is mounted for rotation therewith and to which said seventh axial load is transmitted; an intermediate drive shaft; a third pair of sets of helical splines, the one on said first compressor shaft and the other on said intermediate drive shaft, whereby torque can be transmitted from said first compressor shaft to said intermediate drive shaft and whereof the helix lead on said first compressor shaft is in the same sense as the direction of rotation so that, when torque is so transmitted, an eighth axial load is generated in said first compressor rotor shaft opposing said sixth axial load and a ninth axial load is generated in said intermediate drive shaft; a helical toothed pinion on said intermediate drive shaft; a lay shaft; a first helical toothed gear Wheel on said layshaft meshing with said helical toothed pinion, whereby torque can be transmitted from said intermediate drive shaft to said lay shaft and whereof the helix lead of said pinion is in the same sense as the direction of rotation so that when torque is so transmitted a tenth axial load is generated in said intermediate drive shaft opposed to said ninth axial load and an eleventh axial load is generated in said lay shaft; a second helical toothed gear wheel on said lay shaft; a helical toothed annulus on said fluidscrew shaft meshing with said second helical toothed gear wheel whereby torque can be transmitted from said layshaft to said fiuidscrew shaft and whereof the helix lead of said second gear is in the same sense as the direction of rotation so that when torque is so transmitted, a twelfth axial load is generated in said lay shaft opposed to said eleventh axial load and a thirteenth axial load is generated in said fiuidscrew shaft opposed to said seventh axial load; the helical toothed pinion, helical toothed gear wheels and helical toothed annulus being so relatively dimensioned that they constitute a reduction gear train; a fourth 10 locating thrust bearing for said fluidscrew shaft;

6 a fifth locating thrust bearing for said lay shaft, and a sixth locating thrust bearing for said intermediate drive shaft.

JAMES ALEXANDER PETRIE.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,375,006 Larrecq May 1, 1945 2,583,872 Newcomb Jan. 29, 1952 

